├── makefile
└── rollingStrings.c


/makefile:
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 1 | 
 2 | all:rollingStrings
 3 | 
 4 | rollingStrings:rollingStrings.o
 5 | 	gcc rollingStrings.o -o rollingStrings -Wall -g -std=gnu99
 6 | 
 7 | rollingStrings.o:rollingStrings.c
 8 | 	gcc rollingStrings.c -c -Wall -g -std=gnu99
 9 | 
10 | clean:
11 | 	rm -fr rollingStrings rollingStrings.o
12 | 


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/rollingStrings.c:
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  1 | #include <stdlib.h>
  2 | #include <stdio.h>
  3 | #include <string.h>
  4 | 
  5 | #define SIZE 14
  6 | #define LINE 100
  7 | 
  8 | char *arrayOfStrings[SIZE];
  9 | int j = 0;
 10 | int full = 0;
 11 | 
 12 | 
 13 | char *readOneStr(FILE *fp, int *err);
 14 | 
 15 | // insert string and resort array
 16 | void insertStr(char *r)
 17 | {
 18 |     int i = 0;
 19 |     int k = 0;
 20 |     char *tmp = NULL;
 21 |     if (j == SIZE) {
 22 |         // replace first str
 23 |         free(arrayOfStrings[0]);
 24 |         for (i = 0; i < SIZE-1; i++) {
 25 |             arrayOfStrings[i] = arrayOfStrings[i+1];
 26 |         }
 27 |         // insert new str
 28 |         arrayOfStrings[j-1] = r;
 29 |     }
 30 |     else {
 31 |         // insert new str
 32 |         arrayOfStrings[j++] = r;
 33 |     }
 34 | 
 35 |     // sort the strs
 36 |     for (i = 0; i < j; i++) {
 37 |         for (k = i; k < j; k++) {
 38 |             if (arrayOfStrings[i] == NULL || arrayOfStrings[k] == NULL)
 39 |                 continue;
 40 |             if (strcmp(arrayOfStrings[i], arrayOfStrings[k]) > 0) {
 41 |                 tmp = arrayOfStrings[i];
 42 |                 arrayOfStrings[i] = arrayOfStrings[k];
 43 |                 arrayOfStrings[k] = tmp;
 44 |             }
 45 |         }
 46 |     }
 47 | }
 48 | 
 49 | char *readOneStr(FILE *fp, int *err)
 50 | {
 51 |     int n = 0;
 52 |     char c;
 53 |     int i = 0;
 54 |     char *r = NULL;
 55 |     char buf[LINE];
 56 |     int ret = 0;
 57 |     int k;
 58 | 
 59 |     while (1) {
 60 |         // if file is end, return NULL
 61 |         if (feof(fp)) return NULL;
 62 |         // read n
 63 |         ret = fscanf(fp, "%d", &n);
 64 |         // if n is negative, return NULL
 65 |         if (ret == -1) return NULL;
 66 |         if (n > 0) {
 67 |             // alloc memory for str
 68 |             r = (char *) malloc(sizeof(char) * (n + 1));
 69 |             // init str
 70 |             memset(r, 0, sizeof(char) * (n + 1));
 71 |             if (r == NULL) return NULL;
 72 |             // read str
 73 |             fscanf(fp, "%s", buf);
 74 |             strncpy(r, buf, n);
 75 | 
 76 |             insertStr(r);
 77 |             // output current strings
 78 |             printf("Current strings:\n  0: HEAD\n");
 79 |             for (k = 0; k < SIZE; k++) {
 80 |                 if (arrayOfStrings[k] == NULL) {
 81 |                     printf("  %d: <null>\n", k + 1);
 82 |                 } else {
 83 |                     printf("  %d: %s\n", k + 1, arrayOfStrings[k]);
 84 |                 }
 85 |             }
 86 |             printf("  %d: TAIL\n", k + 1);
 87 |             for (i = n; i < strlen(buf); i++) {
 88 |                 c = buf[i];
 89 |                 printf("OOPS: Non-numeric input detected.  The byte was: 0x%x='%c'.\n", c, c);
 90 |                 *err = 1;
 91 |             }
 92 |             break;
 93 |         } else if (n < 0) {
 94 |             printf("OOPS: The length read from input, %d, was zero or negative.\n", n);
 95 |         }
 96 |     }
 97 | 
 98 |     return r;
 99 | }
100 | 
101 | 
102 | int main(int argn, char *argv[]) {
103 | 
104 |     int i;
105 |     int k;
106 |     FILE *fp;
107 |     int err = 0;
108 |     char *ret = NULL;
109 |     printf("There are %d command-line arguments\n", argn-1);
110 |     for (k = 0; k < SIZE; k++) {
111 |         arrayOfStrings[k] = NULL;
112 |     }
113 |     for (i = 1; i < argn; i++) {
114 |         // open file
115 |         fp = fopen(argv[i], "r");
116 |         if (fp == NULL) {
117 |             fprintf(stderr, "ERROR: Cannot open the file '%s'\n", argv[i]);
118 |         }
119 |         else {
120 |             printf("--- FILE: %s (argv[%d]) ---\n", argv[i], i);
121 |             do {
122 |                 // read one str
123 |                 ret = readOneStr(fp, &err);
124 |             } while (ret != NULL);
125 |             printf("--- END OF FILE ---\n");
126 | 
127 |             fclose(fp);
128 |         }
129 |     }
130 |     // free memory
131 |     for (k = 0; k < SIZE; k++) {
132 |         if (arrayOfStrings[k] != NULL) {
133 |             free(arrayOfStrings[k]);
134 |             arrayOfStrings[k] = NULL;
135 |         }
136 |     }
137 |     return err;
138 | }
139 | 


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